1. Field of the Invention
This invention relates to the art of making translucent soap bars and more particularly to improving the lime soap dispersancy of such bars, and adding a deodorant non-germicidal ingredient thereto without impairing the translucency.
2. The Prior Art
Soap making is an ancient art whose basic precepts are still employed in present day manufacturing plants. One of the ancient specialties of soap making is the art of compounding translucent and transparent bars which, for the purposes of this disclosure, may be lumped under the single category "translucent bars." Because of their attractive appearance, translucent bars command a limited but significant share of the market. The optimum qualities of a translucent bar soap in the prior art are taught in U.S. Pat. No. 3,864,272.
But for the influence of certain problems hereafter discussed, translucent bars might have a significantly larger and more important share of the market. Among the problems of the prior art is the difficulty in making a translucent bar which performs well in hard water, and especially one that is deodorant and non-germicidal.
In many parts of this country and other parts of the world, the water is "hard" by reason of the presence of bivalent ions such as, for example, magnesium and calcium, which combine with the fatty acids of soap to form an insoluble product known as "lime soap." A soap that performs well in hard water must have the ability to disperse and hold in solution this lime soap, which property will sometimes hereafter be referred to as lime soap dispersancy.
The prior art workers succeeded in making a translucent soap bar which is deodorant and/or germicidal or a translucent bar which performs reasonably well in hard water, but they have not been able to make a deodorant, non-germicidal, translucent bar that performs well in hard water.
Thus, in hard water areas, users have to forego either translucency or deodorancy because lime soap dispersancy in such areas is absolutely essential. Moreover, a need exists for an ordinary translucent bar with improved lime soap dispersancy.
These problems represent an existing need felt by the user and the soap industry, and they have been met by means of the instant invention.
3. Brief Summary of the Invention
It has been discovered that the combination of a soap base, a citronellyl ester (such as, for example, citronellyl senecioate, citronellyl formate, citronellyl acetate and citronellyl isobuterate) and a suitable alcohol, especially one or more polyalkylene glycols having a molecular weight between about 200 and about 4,000, preferably those selected from the group consisting of polyethylene glycol having a molecular weight from about 600 to about 1500, and/or one or more polyhydric alcohols having a molecular weight between about 62 and about 342, preferably those selected from the group consisting of diols and triols having a molecular weight from about 76 to about 134, is a significantly better translucent soap having improved lime soap dispersancy; and in at least one instance (citronellyl senecioate) it adds deodorant activity to the soap bar without destroying its translucent character.
A concentration of a citronellyl ester of at least about 1.0 weight percent is required for noticeably effective results--the upper limit being dictated by economics--for a translucent bar that exhibits deodorancy. Inasmuch as citronellyl senecioate has a demonstrated deodorancy (see U.S. Pat. No. 3,493,650 to Universal Oil Products), it may be inferred that the other citronellyl esters also have deodorancy.
A range of concentration from about 0.5% to 5% of polyalkylene glycol and/or polyhydric alcohol is ideal for satisfactory results. Examples of polyols useful in this invention are, among others, butanediol, hexylene glycol, 1,5-pentanediol, cyclohexanediol, and sugars such as sucrose and sorbitol. Examples of polyalkylene glycols are polyoxypropylene glycol and polyoxybutylene glycol. As much as 30% by weight of a soap bar could be added, but much lower concentrations are preferred.
A soap suitable for the translucent bar of this invention is a long chain fatty acid neutralized by a suitable alkali metal hydroxide, preferably sodium and/or potassium hydroxide. It is also preferable to use a slight excess of the alkali metal hydroxide in the neutralization step to improve soap stability. The fatty acids employed may be obtained from any typical fatty acid source that is consistent with the state of the art. The soap composition may also contain additional additives consistent with the state of the art such as silica and clarifying agents, emollients, perfumes, color, etc.
Subject to the above remarks, a preferred translucent soap is one made according to the teachings of U.S. Pat. No. 3,864,272 to Toma, et al, in combination with a citronellyl ester, e.g., citronellyl formate, citronellyl acetate, citronellyl isobuterate, and citronellyl senecioate. As taught in the said patent, in some combinations containing only one of the glycols or polyols, the addition of glycerine, suitably from about 1-3 percent based on the weight of the soap is necessary.